Gas Turbine Combustor Flange Slit Design for Thermal Stress Relief
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Solution Overview
Problem
The combustor transition pipe in gas turbines experiences thermal stress due to temperature differences between high-temperature and low-temperature regions, leading to stress concentration at the pin hole, resulting in cyclic fatigue during repeated operation and shutdown cycles.
Innovation Solution
Incorporating circumferential and radial slit portions in the flange portion of the combustor transition pipe, which relaxes thermal stress by allowing thermal expansion and reducing stress concentration around the pin hole.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the flange portion is made rigid to ensure structural strength, then the structural strength is improved, but thermal stress concentration occurs at the pin hole due to temperature differences between high-temperature and low-temperature regions
Solution Approach 1:
The flange portion is segmented by providing circumferential slits and radial slits that divide the continuous structure into sections. These slits allow different parts of the flange to expand and contract independently in response to thermal gradients, reducing stress concentration at the pin hole while maintaining overall structural integrity through the distributed slit pattern.
Solution Approach 2:
The slit configuration is strategically designed with circumferential slits positioned to address thermal stress in specific regions and radial slits arranged to accommodate localized thermal expansion. The slits are distributed non-uniformly throughout the flange portion, with higher density in high-stress areas, allowing localized stress relief while preserving strength in critical load-bearing regions.
2Stress or pressure
If the flange portion is made flexible to reduce thermal stress, then thermal stress is reduced, but the structural strength and rigidity deteriorate
Solution Approach 1:
The flange portion is segmented by providing circumferential slits and radial slits that divide the continuous structure into sections. These slits allow different parts of the flange to expand and contract independently in response to thermal gradients, reducing stress concentration at the pin hole while maintaining overall structural integrity through the distributed slit pattern.
Solution Approach 2:
The slit configuration is strategically designed with circumferential slits positioned to address thermal stress in specific regions and radial slits arranged to accommodate localized thermal expansion. The slits are distributed non-uniformly throughout the flange portion, with higher density in high-stress areas, allowing localized stress relief while preserving strength in critical load-bearing regions.
3Productivity
If the gas turbine is repeatedly operated and stopped, then productivity is improved, but cyclic fatigue occurs at the pin hole due to repeated thermal stress
Solution Approach 1:
The flange portion is segmented by providing circumferential slits and radial slits that divide the continuous structure into sections. These slits allow different parts of the flange to expand and contract independently in response to thermal gradients, reducing stress concentration at the pin hole while maintaining overall structural integrity through the distributed slit pattern.
Solution Approach 2:
The slit configuration is strategically designed with circumferential slits positioned to address thermal stress in specific regions and radial slits arranged to accommodate localized thermal expansion. The slits are distributed non-uniformly throughout the flange portion, with higher density in high-stress areas, allowing localized stress relief while preserving strength in critical load-bearing regions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The slits effectively reduce cyclic fatigue by distributing thermal stress, extending component replacement cycles and maintenance intervals in gas turbines.
Implementation Method 1
the flange portion includes a circumferential slit portion either extending within a range in a radial direction where the pin hole is formed or being located on radially outside of the pin hole and extending in the circumferential direction... relax thermal stress in the vicinity of the pin hole
Data Source
AI summary
The present invention is a combustor provided with a combustor transition pipe connected to a turbine while interposing a transition pipe seal in between, including a flange portion provided at an end portion on a downstream side in a fluid flow direction of the combustor transition pipe, the flange portion projecting to radially inside and extending in a circumferential direction. The flange portion includes a pin hole into which a pin to position the transition pipe seal is inserted, a circumferential slit portion either extending within a range in a radial direction where the pin hole is formed or being located on radially outside of the pin hole and extending in the circumferential direction, and a hole portion on which part of the circumferential slit portion abuts.